Outbreak may be over, but state officials say cases demonstrate dangers of eating raw dairy products

At least 25 Minnesotans have been sickened with salmonellosis linked to eating a raw Mexican-style cheese, queso fresco, state health officials said. The outbreak illustrates the dangers of consuming unpasteurized dairy products.

The Minnesota Department of Health (MDH), the Minnesota Department of Agriculture (MDA) and the City of Minneapolis have been investigating the outbreak and the source of the raw milk used to make the cheese since the first cases were detected in late April.

MDH confirmed 18 cases of infection with the same strain of Salmonella. An additional seven cases of illness occurred among family members or other contacts of confirmed cases, but no laboratory specimens were available. The individuals became ill between March 28 and April 24. Of the 25 cases, 15 were hospitalized. All have recovered. Many cases reported eating unpasteurized queso fresco purchased or received from an individual who made the product in a private home. Investigators have determined that the individual made home deliveries and also may have sold the product on a street corner near the East Lake Street area of Minneapolis.

Anyone who may have purchased or received this product recently should not eat it but should throw it away.

Samples of unpasteurized queso fresco collected from the cheese maker were found to contain the same strain of Salmonella as the illnesses. Investigators determined that the milk used to make the cheese was purchased by the cheese maker from a Dakota County farm. Unpasteurized milk samples collected at the farm were also found to match the outbreak strain.

Dr. Heidi Kassenborg, director of MDA's Dairy and Food Inspection Division, said the outbreak underscores the dangers of consuming unpasteurized dairy products. "It only takes a few bacteria to cause illness. Milking a cow is not a sterile process and even the cleanest dairy farms can have milk that is contaminated. That's why pasteurization - or the heat treatment of milk to kill the harmful pathogens - is so important," said Kassenborg.

Minnesota law allows consumers to purchase raw milk directly from the farm for their own consumption, but it may not be further distributed or sold. Additionally, cheese production facilities need to follow proper food safety laws and regulations, including licensure.

Dr. Carlota Medus said the outbreak may be over, as there are no suspect cases pending. However, it may still be possible to see additional cases that have not been reported yet from people who consumed cheese prior to health officials' interventions, which occurred April 23-26.

While this particular outbreak may be over, MDA and MDH officials are concerned that this may not be an isolated incident: that there may be other instances of people buying foods like unpasteurized queso fresco prepared by neighbors, friends or family. "It's important for people to be aware of the inherent risk of consuming any raw dairy product from any source," Medus said. "We encourage people to think carefully about those risks and know that the risks are especially high for young children, pregnant women, the elderly and those with weakened immune systems."

Salmonella bacteria can cause serious and sometimes fatal infections, especially in high risk groups. Healthy people infected with Salmonella often experience diarrhea, fever, and abdominal pain. Symptoms often begin 12-72 hours after consumption of contaminated food but can begin up to a week or more later. Anyone who believes they may have become ill with Salmonella should contact their health care provider.
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